The pupose of the proposed research is to investigate the effects of rearing kittens with surgically or optically induced convergent strabismus during the critical developmental period upon the response properties of retinal ganglion cells. Our previous investigations of the visual system of the Siamese cat, a congenitally strabismic organism, have revealed that the receptive field properties of retinal ganglion cells are quite abnormal compared to those in common cats. Our preliminary data on the effects of surgically induced strabismus in common cats suggest that many of the response properties in these animals exhibit similar anomalies to those found in cross-eyed Siamese cats. The proposed research is a continuation of our efforts to systematically investigate the retinal changes which may develop as a consequence of a convergent strabismus induced during early infancy. The identification of major alterations in receptive field properties and the investigation of possible mechanisms involved in such abnormal development will be emphasized during the proposed project period. Extracellular single cell recordings will be made from the optic tract to monitor the activities of retinal ganglion cells in strabismic and control cats. Various stimulus conditions will be presented to the subject during the recordings in order to assess the primary effects. Some of the proposed experiments will be specifically designed to investigate the origins or the abnormal development. Procedures for this purpose include the utilization of prisms, defocusing lenses, and lid-suturing.